Structure of aqueous copper chloride solutions: results from Monte Carlo simulations at various concentrations

Abstract

Monte Carlo simulation results are reported for aqueous copper chloride solutions in the concentration range (1–5 mol kg^–1) and compared with experimental data on the species formation and structure of these solutions. The structural data from the simulations suggest which of the quite contradictory interpretations of experimental results is to be preferred. Special emphasis was given to the formation of CuCl^(2–n)–_n complexes, and the formation constants evaluated from the simulation are in good agreement with experimental data, underlining the reliability of the structural data. Whereas in 1 mol kg^–1 solution direct copper–chloride binding does not occur, CuCl⁺ is the dominant species in 3 mol kg^–1 solution. In 5 mol kg^–1 solution, complexes of copper with 1–4 chloride ions are observed. Structural details of the complexes are visualized by ligand distribution plots, showing a breakdown of the order of the hydration structure at high salt concentrations. Indications were obtained that CuCl⁺ is the main active species inducing peptide condensation of amino acids in aqueous solution.